Substances are often used in the pharmaceutical, cosmetic, and also in technical industries, which consist of two or more components. These substances are characterized by the fact that they cannot be stored or can only be stored to a limited extent in the mixed state. This is true, for example, for synthetic resins, which are provided with a hardener in the pourable state, so that they harden after a certain reaction time.
However, there are also cosmetic substances, which should be brought together only during or directly before application in order to develop specific properties.
In the case of these two-component substances, as a rule, a specific mixing ratio of the two components is to be maintained in order to obtain, e.g., a sufficiently long processing time and/or a possibly complete reaction of the two material components. In the mixed state, such substances cannot be stored, since the chemical reaction generally occurs in an irreversible way and ensues directly after mixing the two components. It therefore happens that these two components are dispensed in a specific mixing ratio directly before the processing or application. The two material components are usually stored in separate containers and are removed from these containers in the appropriate proportions and dispensed for direct subsequent mutual processing.
Pump dispensers of this type are known, by means of which it is possible to obtain a prescribed mixing ratio of the two components, even if different total quantities are required. These pump dispensers have two metering pumps, which simultaneously feed two material components from supply containers associated with the metering pumps, upon actuating a common actuation unit.
A pump dispenser of this type is known from German patent DE-A 3,614,515 and consists of an essentially oval connection cap, which is provided on the underside with two connection cylinders arranged next to each other. The connection cylinders essentially determine the oval outer contour of the connection cap and are each provided with an inner threading into which a supply container with its bottleneck-type connection fittings is screwed. The distance between the connection cylinders is thus selected such that the supply containers can be screwed in individually and independent of one another. The connection cap has on the upper side lying opposite the connection cylinders an oval ring or piston land surrounding the connection cylinders and axially projecting upward.
A feed pump is plugged into the uptake cylinder from the threaded side. The supply containers and the metering pumps associated with them are coaxially arranged next to each other and lie in the common longitudinal central plane of the connection cap. The feed pumps are provided on the upper side with an outlet tube, which open up each time into an output channel of the common actuating device. The outlet tubes of the metering pumps are thus attached by means of a catch connection in the respective output channel. The actuating device is adapted in its form to the oval shape of the connection cap, whereby it is provided with an outer wall aligned toward the bottom, which is completely immersed in the ring land of the connection cap. An outlet channel leads from the outlet tubes of the feed pumps each time to a common outlet opening of the actuating device. In another variant, these two outlet channels of the actuating device open up into outlet nozzles each arranged separately from the other, the output openings of which are arranged in the direct vicinity of each other.
When the actuating device is compressed, both feed pumps are actuated simultaneously, so that the two material components are simultaneously supplied to the outlet opening from the supply containers through the respective outlet channel. In one complete pump stroke up to the stop on the under side of the outer wall of the actuating device on the upper side of the connection cap, each of the two metering pump feeds a maximum quantity of material components, whereby these quantities are related by the respective pump volumes of the metering pumps in a specific ratio which is given beforehand and unchangeable. Since the actuating device is only plugged onto the outlet tube of the two metering pumps and guide elements are not provided, which respectively hinder a tilting or an oblique compression of the actuating device, a uniform and simultaneous feed stroke of the two metering pumps is possible only under certain conditions.
The pumps each travel the same feed path, i.e., beginning simultaneously with pressure on the actuating device with the feed stroke, and also travel the same path during the stroke motion, so it is necessary that the actuating device is actuated symmetrically to the feed pumps arranged next to each other. In the case of an asymmetric actuation of the actuating device, the beginning of feed of one metering pump occurs prior to the beginning of feed of the neighboring metering pump. This leads to different mixing ratios of the two material components in the case of small output quantities, such as if a complete feed stroke is not carried out. The two metering pumps travel the same feed stroke, i.e. the maximum stroke, and deliver substantially equal amounts only if the actuating device is completely compressed up to the stop. Only in this case can a pregiven mixing ratio be maintained. This means that with small feed quantities, i.e., in the case of a feed stroke that is smaller than the maximum, and, for example, with asymmetric actuation of the actuating device, the desired mixing ratio cannot be assured due to the different pump paths of the two feed pumps.
Further, a change in the mixing ratio of the two material components is possible exclusively due to the use of metering pumps with different maximum stroke volumes. That is, for a change in the mixing ratio, it is necessary to exchange at least one of the metering pumps completely for a metering pump with another stroke volume, whereby the pump dispenser must be almost completely dismantled. A variable use of this known pump dispenser is thus not possible without great expense, since several different metering pumps must be prepared for different mixing ratios and their exchange is associated with a number of assembly steps.
A paste dispenser is also already known from U.S. Pat. No. 4,438,871, which does not have a communication bellows as a pump device, but rather two manually actuatable pump pistons. The pump pistons take in two different media simultaneously, in cooperation with intake valves, from two paste containers lying concentrically within one another, but separate. Each of the two paste containers is provided with a lagging piston and supply the media via separate channels into a backup space, which is arranged directly in front of an outlet opening. This backup space surrounds a tappet-type closing organ which is arranged on an elastic membrane wall loaded by the feed pressure of the medium.
The two pump pistons are arranged coaxially to each other, joined rigidly together and are provided with a common actuating device, which is manually actuated. In order to pump different quantities, the pump pistons are provided with different diameters. The cylindrical pump chambers which are also coaxial and are combined with the separate paste containers by means of intake valves. Two separate conduction channels join the cylindrical pump chambers by separate outlet valves. These channels run axis-parallel and are arranged eccentrically to the pump chambers and open up into the backup space. In this way a labyrinth-type shape of the space is produced of the pump chambers and conduction channels that are joined together. The manufacturing technology for this pump device can only be realized with difficulty and at high cost, so that this device is unsuitable for mass production, especially if it is a so-called disposable article.
In other known two-component paste dispensers, U.S. Pat. Nos. 4,773,562 and 4,949,874, the pump organs consisting of pistons are arranged parallel to each other in a container head and can be actuated jointly by means of a bridge-type actuating device with the same size stroke and with the same stroke volume. In one of these two paste dispensers, U.S. Pat. No. 4,949,874, there is also the possibility of actuating the two pistons individually.
In addition, two-component metering dispensers are also known from German Unexamined patent disclosures DE-OS 3,837,704 and 3,843,759, which have a communication bellows as the pump organ. In this case, however, the second component is added to a first quantity-dominant material component only in small, rigidly prescribed quantities, e.g., in strip form. The quantity ratio cannot be varied. The metering dispensers in DE-OS 3,837,704, provides a communication bellows with an intake and an outlet valve for the primary material component and a feed piston for the second material component. This piston is loaded by the primary material component and is arranged in a cylindrical container space filled with the second material component. In the other metering dispenser, DE-OS 3,843,759, the communication bellows itself is filled with the second material component, which it provides to the output channel by means of secondary channels. The primary material component, however, is conducted through a tube channel that is essentially greater in its cross section and coaxially projects through the communication bellows. The quantity ratios between the two material components also cannot be influenced in a controlled manner in this case. Rather, the prescribed quantity ratio is maintained only somewhat precisely for these two-component metering dispensers, if a complete actuation stroke is carried out and the two materials have at least approximately the same viscosity.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.